Electrical insulation arrangements for electric fans, motor assemblies and controls therefor

ABSTRACT

The present invention generally provides electrical insulation arrangements for electric fans, motor assemblies and controls therefor. According to a particular aspect of the invention, an electric motor for an electric fan having a fan housing is provided. The motor comprises a motor casing having an insulator mounting arrangement configured for mounting the motor to the fan housing. The mounting arrangement comprises a mounting portion of the motor casing, and an insulating member mounted to the mounting portion of the motor casing without a separate fastener. The insulating member is configured to accept a fastener that can be utilized to mount the motor casing to the fan housing such that the fan housing would be insulated from the motor casing. Other aspects are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a divisional of copending application Ser. No.10/696,647 filed Oct. 29, 2003, upon which a claim of priority isbased.”

TECHNICAL FIELD

The invention relates to electric fans, and more particularly toelectric fans having electric motor assemblies and related componentsmounted therein.

BACKGROUND OF THE INVENTION

Electric fans of all types have traditionally been an effective way toprovide climate control within a living space. During the summer months,electric fans provide a very low cost solution to keep air circulatingwithin a living space, and hence, help keep temperatures from reachinguncomfortable, and sometimes dangerous, levels. In recent years,electric fans have been made increasingly efficient and more powerfulthrough advancements in electric motor technology. Many electric fanstoday, such as box fans, incorporate four pole and six pole splitcapacitor motor technology. While this technology increases efficiencyand power, it does require relatively higher operating voltages.

While existing electric fan assemblies have all been designed to be safefor their intended use, it is desirable to not only meet, but exceedsafety standards set by various organizations, including independentorganizations such as Underwriters Laboratories (UL). With this goal inmind, it is desirable to electrically isolate electric motors from otherportions of the fan assembly. This is especially true when the fan isbeing operated in very humid conditions or when the air being moved bythe fan has high moisture content. Condensation caused by the air cancreate a current leakage pathway between the fan motor and other partsof the fan, such as a metallic shroud of a typical box-type fan. In suchcases, these other parts of the fan can become electrically charged.Electrical isolation of the fan motor prevents such occurrences.

Presently-known attempts at electrical isolation have many drawbacks.For example, U.S. Pat. No. 6,309,192 discloses an insulated box fan thatemploys a plastic isolator ring that is attached to the fan housing at afirst set of points and separately attached to the fan motor at a secondset of points. The attachments are implemented with screws. One problemassociated with this fan is the difficulty in alignment of theattachment points between the isolator ring and the motor. Thisdifficulty is created by the ring being a single component havingmultiple attachment points. Because all of the attachment points arefixed to a single component, alignment of the attachment points arelinked together, thereby creating alignment and tolerance constraints.This creates manufacturing quality concerns. Furthermore, because theisolator ring is a single component, it is more susceptible tomanufacturing defects caused by inconsistencies between each of theattachment points, dimensional or otherwise. Another problem is the costof the components and the assembly. Because of the multiple attachmentpoints, the number of screws needed for the attachment points, the sizeof the isolator ring, and other factors, the assembly is relativelycostly.

It has also been found that a combination of insulating solutions can bemore effective than merely incorporating an insulator between the motorand the fan housing as shown in the '192 patent. Among its othershortcomings, the '192 patent does not disclose any such additionalinsulating solutions.

SUMMARY OF THE INVENTION

The present invention generally provides electrical insulationarrangements for electric fans, motor assemblies and controls therefor.

According to a particular aspect of the present invention, an electricmotor for an electric fan having a fan housing is provided. The motorcomprises a motor casing having an insulator mounting arrangementconfigured for mounting the motor to the fan housing. The mountingarrangement comprises a mounting portion of the motor casing, and aninsulating member mounted to the mounting portion of the motor casingwithout a separate fastener. The insulating member is configured toaccept a fastener that can be utilized to mount the motor casing to thefan housing such that the motor casing and the fan housing are insulatedfrom each other.

According to another aspect, an insulated mounting arrangement formounting an electric motor to a fan housing of an electric fan isprovided. The arrangement comprises a mounting portion of the motorcasing, an insulating member mounted to the mounting portion of themotor casing without a separate fastener, and a fastener disposedthrough a portion of the fan housing and within the insulating membersuch that the fastener is insulated from the motor casing.

According to another aspect, an electric motor for an electric fanhaving a fan housing is provided. The motor comprises a motor casinghaving an insulator mounting arrangement configured for mounting themotor to the fan housing. The mounting arrangement comprises a mountingportion of the motor casing, and an insulating member mounted to themounting portion of the motor casing without a separate fastener todefine a general point of attachment. The insulating member isconfigured to accept a fastener that can be utilized to mount the motorcasing to the fan housing at the general point of attachment such thatthe fastener would be insulated from the motor casing.

According to yet another aspect, an insulated mounting arrangement formounting an electric motor to a fan housing of an electric fan isgenerally provided. In one embodiment, the arrangement includes amounting portion of a motor casing of the motor having a mountingaperture therein, an insulating member having at least a portiondisposed within the mounting aperture of the motor casing, and a screwdisposed through a portion of the fan housing and within the insulatingmember such that the screw is insulated from the motor casing.

According to another aspect, the insulating member includes a baseportion and a protrusion extending therefrom, the protrusion beingmounted to the mounting portion of the motor casing. In a particularembodiment, the protrusion in press-fit into a mounting aperture withinthe mounting portion of the motor casing.

According to yet another aspect, an insulated mounting arrangement formounting an electric motor to a fan housing of an electric fan isprovided where the arrangement includes a mounting portion of a motorcasing of the motor, an insulating member connected to the mountingportion of the motor casing, and a motor mount portion of the fanhousing. The insulating member is configured to directly engage themotor mount portion of the fan housing without separate fasteners. Theengagement electrically insulates the fan housing from the motor casing.

According to yet another aspect, an electric fan is provided comprisinga fan housing having a peripheral shroud portion and a front and a reargrill portion each disposed adjacent the shroud portion. The shroudportion and the grill portions define an interior region of the fanhousing within which a motorized blade assembly is mounted to a motormount portion of the fan housing such that the motorized blade assemblyis electrically insulated from the fan housing. The motorized bladeassembly includes a motor having a motor casing. The motor casingincludes a vented rear surface disposed adjacent to the rear grillportion. The rear grill portion includes a first mesh portion and asecond mesh portion defined by a plurality of openings within the reargrill portion. The second mesh portion is disposed adjacent to thevented rear surface of the motor casing. The openings of the second meshportion are dimensioned such that a user's finger cannot passtherethrough and contact the motor casing while allowing sufficient airflow to cool the motor.

According to another aspect, an electric fan having at least one controlis provided. The fan comprises a fan housing and a control casingattached to the fan housing and configured to house the at least onecontrol of the fan. The casing is configured to electrically isolate theat least one control from the fan housing.

According to yet another aspect, an insulated mounting arrangement formounting an electric motor to a fan housing of an electric fan isprovided. The arrangement comprises a mounting portion of a motor casingof the electric motor, an insulating member mounted to the fan housing,and a fastener disposed through the insulating member and within themounting portion of the motor casing such that the fan housing isinsulated from the motor casing and the fastener.

These and other aspects will become apparent from a review of theDrawings, Detailed Description and the Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fan assembly having a portion of arear fan grill cut away to show an insulator mounting arrangement of anelectric motor of the fan assembly in accordance with the principles ofthe present invention.

FIG. 2 is a perspective view of a motor showing a plurality ofinsulating members mounted thereto, one of the insulating members beingshown in exploded view.

FIG. 3 is an elevational view of the motor of FIG. 2 mounted to aportion of a fan housing with screws, two of the mounting areas beingshown in cross-section.

FIG. 4 is a detailed view of one of the mounting areas shown in FIG. 3.

FIG. 5 is a partial cross-sectional view of a mounting area having analternative mounting arrangement utilizing an alternative embodiment ofan insulating member.

FIG. 6 is an assembly view of a motor mount portion of a fan housing andthe alternative insulating member shown in FIG. 5, the motor mountportion including a slot that is configured to cooperate with theinsulating member to mount the motor to the fan housing.

FIG. 7 is a partial cross-sectional view of a mounting area having analternative mounting arrangement utilizing an alternative embodiment ofan insulating member.

FIG. 8 is a plan view of a rear fan grill of the fan assembly shown inFIG. 1.

FIG. 9 is a perspective view of a control module for a fan in accordancewith the principles of the present invention.

FIG. 10 is a partial elevational view of the control module of FIG. 8shown mounted to a fan housing.

FIG. 11 is a partial perspective view of the control module shown inFIG. 9, with one case portion of a case of the module being unattachedto another case portion of the case.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the present invention will be described fully hereinafter withreference to the accompanying drawings, in which one or more particularembodiments is shown, it is to be understood at the outset that personsskilled in the art may modify the embodiments herein described whilestill achieving the desired result of this invention. Accordingly, thedescription which follows is to be understood as an informativedisclosure of one or more specific embodiments in accordance with thegeneral principles of the invention directed to the understanding bypersons skilled in the appropriate arts of those principles, and not aslimitations of the present invention.

Referring to FIG. 1, an embodiment incorporating the principles of thepresent invention is shown as an electric fan assembly 10. The fanassembly 10 includes a fan housing 12 having a peripheral shroud portion14 and two grill portions, a rear grill portion 16 and a front grillportion (not shown). In a particular embodiment suited for applicationof the principles of the present invention, the fan housing 12 is madeof a metallic material and the grill portions are made of a moldedplastic material. Each of the grill portions are disposed adjacent theshroud portion 14. The shroud portion 14 together with the grillportions define an interior region 18 of the fan housing 12 within whicha motorized blade assembly 20 is disposed.

The motorized blade assembly 20 includes a motor 22 having a motorcasing 24. In a preferred embodiment, the motor casing 24 is made of acast metal. As shown in the cut away portion of FIG. 1, the motor 22 ismounted to a motor mount portion of the fan housing 12. In a preferredembodiment, the motor 22 is mounted to a pair of mounting brackets 26 asshown in FIG. 1.

In accordance with the principles of the present invention, the motor 22is mounted to the fan housing 12 in an insulated mounting arrangement.Referring to FIGS. 2-4, the arrangement includes at least one insulatingmember 30 connected to a mounting portion 32 of the motor casing 24.Although the mounting portion 32 is shown in this embodiment as aportion outwardly and radially extending from the motor casing 32, themounting portion can be in any form, and integrated with, or separatelyattached to, the motor casing 24, as long as the mounting portion 32facilitates attachment of the insulating member 30, either directly orindirectly, to the motor casing 24. In a preferred embodiment, there arefour insulating members 30 disposed about the motor casing 24 of themotor 22.

The insulating member 30 preferably includes a base portion 34 having amounting surface 36 and a protrusion 38 extending therefrom. Theprotrusion 38 of the insulating member 30 is configured to be securelydisposed within a mounting aperture 40 of the motor casing 24, therebydefining a general point of attachment to the motor casing 24.Preferably, the protrusion 38 has an interference fit with the mountingaperture 40 and is pressed therein by suitable manufacturing methods.However, the protrusion 38 can be securely disposed within the mountingaperture by any number of means, including by means of adhesive,insertion during casting or molding, snap fitting or other mechanicalfastening arrangement, weldment, etc. According to a particular aspectof the invention, it is preferable that the mounting be facilitatedwithout the use of a separate fastener.

As an alternate embodiment, an insulator member can be completelyintegrated within the motor casing, such as by insertion during casting,wherein the whole insulator member—in lieu of a protrusion, such as theprotrusion 38—could define a general point of attachment. In yet anotherembodiment, a protrusion of the insulator member can be mounted in aradial direction with respect to the motor casing (i.e., generallytransverse to an axis defined by a motor shaft S), in lieu of an axialdirection as shown in FIGS. 2 and 3. In such an embodiment, the generalpoint of attachment would be generally transverse to a direction of themounting of the motor casing to the fan housing (i.e., the axialdirection). In such a case, the mounting of the motor casing to the fanhousing is still considered as being at the general point of attachment,since the mounting is generally positioned within, or adjacent to, aplane in the radial direction extending through the point of attachmentand the axis of the motor shaft S.

If desired, the motor 22 can be supplied as a unit that includes theinsulating members 30 secured thereto and ready for assembly to the fanhousing 12.

According to a particular aspect of the invention, the general point ofattachment can serve as a mounting area for mounting the motor casing tothe fan housing. This is particularly facilitated in embodiments wherethe insulator member is mounted to the motor casing without the use ofseparate fasteners at the general point of attachment, which couldotherwise interfere with the mounting of the motor casing to the fanhousing. In the embodiment shown in FIGS. 1-4, the protrusion 38 of theinsulating member 30 includes a blind hole 42 configured to accept ascrew or fastener 44 (best shown in FIGS. 3 and 4). Preferably, thefastener is a self-tapping or thread-forming screw. As shown in FIGS. 3and 4, the mounting surface 36 of the base portion 34 of the insulatingmember 30 is arranged to oppose a mounting surface 50 of the fan housing12 when the motor 22 is mounted to the fan housing 12 by the fastener44. The fastener 44 passes through the mounting surface 50 of the fanhousing 12 and penetrates the base portion 34 and the protrusion 38 ofthe insulating member 30. As best shown in FIG. 4, the fastener 44 isinsulated from the motor casing 24 when the motor is mounted to the fanhousing 12. The insulating member 30 acts as an electrically insulatingbarrier between the fastener 44 and the motor casing 24 as well asbetween the motor casing 24 and the fan housing 12. Thus, in the case ofa current leakage from the motor 22 that charges the motor casing 24,the current cannot establish a path to the fan housing 12. The mountingsurface 36 of the base portion 34 is preferably designed to be largeenough to prevent moisture from completely tracking across the mountingsurface 36 and grounding the motor casing 24 to the fan housing 12.

According to another aspect of the invention, the insulating member 30can be configured to directly engage the motor mount portion of the fanhousing 12 without separate fasteners. In this type of arrangement, theinsulating member 30 itself would act as both a fastener and aninsulator between the motor casing 24 and the fan housing 12. Thisarrangement can be achieved through the use of a snap fit with a portionof the fan housing 12, a key fit within an aperture arrangement in thefan housing 12, or other suitable arrangement that does not require theuse of a separate fastener. In one particular embodiment as shown inFIGS. 5 and 6, an insulating member 60 is provided, which includes afirst base member 62 and a second base member 64 having a neck portion66 disposed therebetween. The insulating member 60 also includes aprotrusion 68 that engages the mounting aperture 40 of the motor casing24. The neck portion 66 is configured to engage a slot 70 within a motormount portion 72 of a fan housing and the base members 64 and 66 of theinsulating member 60 cooperate to engage the motor mount portion 72.Numerous other embodiments are contemplated having the common feature ofavoiding the use of separate fasteners for mounting the motor to the fanhousing.

According to another aspect of the invention, insulation between themotor casing 24 and a portion of a fan housing 73 is facilitated byincorporating one or more insulating members 74 that are mounted withinan aperture 75 of the portion of the fan housing 73 as shown in FIG. 7.In this embodiment, the insulating member 74 has a first portion76—defining an insulating portion between the motor casing and theportion of the fan housing—and a second portion 77—defining aninsulating portion between the portion of the fan housing 73 and afastener 78. In such an embodiment, the fastener 78 can be allowed topenetrate the motor casing 24 while still being isolated from the fanhousing 73. In a preferred embodiment according to this aspect of theinvention, the insulating member 74 is a grommet or grommet-like elementmade of a resilient insulating material.

According to yet another aspect of the present invention, the rear grillportion 16 includes a first mesh portion 80 concentrically disposedabout a centrally disposed first solid surface portion 81 and a secondmesh portion 82 concentrically disposed about the first mesh portion 80,as shown in FIG. 8. A second solid surface portion 84 is disposedtherebetween. The mesh portions 80 and 82 are defined by a plurality ofopenings within the rear grill portion 16, as best shown in FIG. 8. Thefirst mesh portion 80 is configured to be disposed adjacent to a ventedrear surface 86 of the motor casing 24 in the fan assembly, as shown inFIG. 1. The openings of the first mesh portion 80 are dimensioned suchthat a user's finger cannot pass therethrough and contact the motorcasing 24 while still allowing sufficient air flow to cool the motor 22.The solid surface portion 84 provides an additional barrier between themounting area and the user. The second mesh portion 82 also provides anadditional barrier while still allowing air to flow therethrough. Thesefeatures, alone and in combination, contribute to an insulating barrierbetween the motor 22 and the user.

In fan embodiments that do not incorporate motor assemblies havingcontrols that are integrated into the motor casing or disposed adjacentthereto—such as, for example, the motor 22 as depicted in FIGS. 1-3,wherein the controls are isolated via the insulator members—it may bedesirable to separately isolate the controls and associated electricalperipherals. Referring to FIGS. 9-11, a control module 100 having acasing 102 is depicted, wherein one or more controls and associatedelectrical peripherals (such as a plug receptacle, a light or LEDindicator, a fuse holder, associated wiring and/or wiring connections,terminals, etc.) of the fan are isolated from surrounding componentsthat may conduct electrical current to a user, such as a fan housing103. In the embodiment shown, the control casing 102 includes a firstcasing portion 104 and a second casing portion 106. The casing portionsmay include attachment features in the form of one or more snapprotrusions 108 and corresponding latch features 110, as shown in FIGS.9-11, which facilitate attachment of the casing portions 104 and 106 toeach other. In this particular embodiment, the casing portions 104 and106 include a hinge 111 (shown in FIG. 11) that hingedly connects thecasing portions 104 and 106 together. Preferably, the hinge is formedfrom a web of material that is contiguous with the casing portions 104and 106. However, the casing portions 104 and 106 could also becompletely separable. Although this is a preferable attachmentarrangement, which could allow disassembly of the casing portions ifdesired, the casing portions could also be permanently attached to eachother, such as by adhesive, weldment (such as sonic weldment), or othermeans. In such an embodiment, the control module 100 could be treated asa single drop-in replaceable module.

One or both of the casing portions 104 and 106 may also include anattachment feature to facilitate attachment to the fan housing 103, suchas one or more snap protrusions 112, which engage the fan housing 103via one or more corresponding snap apertures 114 within the fan housing103. When assembled in a fan assembly, the casing 102 provides isolationof electrical componentry, which alone or in combination with otheraspects of the invention described herein, contributes to providing aninsulating barrier between electrical elements of the fan assembly andthe user.

While one or more specific embodiments have been illustrated anddescribed, numerous modifications may come to mind without significantlydeparting from the spirit of the invention, and the scope of protectionis only limited by the scope of the accompanying Claims.

1. An electric fan having at least one control, the fan comprising: afan housing; and a control casing attached to the fan housing andconfigured to house the at least one control of the fan, the casingconfigured to electrically isolate the at least one control from the fanhousing.
 2. A control module for an electric fan having a fan housing,the control module comprising: at least one control configured to beconnectable to an electrical circuit associated with the fan; and acasing having an interior portion containing the at least one controlassociated with the fan, the casing configured to be attachable to thefan housing and configured to electrically insulate the at least onecontrol from the fan housing when it is attached to the fan housing,while allowing access to the control by a user of the fan.
 3. Anelectric fan comprising: a fan housing; a motorized blade assemblydisposed within the fan housing, the motorized blade assembly includingan electric motor having a motor casing mounted to the fan housing; aninsulating member disposed between the fan housing and the motor casingto electrically insulate the motor casing from the fan housing; at leastone control associated with an electrical circuit of the fan; and acasing having an interior portion containing the at least one controlassociated with the fan, the casing mounted to the fan housing andconfigured to electrically insulate the at least one control from thefan housing.